Like the entire Earth X trilogy, this issue touches on a number of subjects that deal with the entire history of the Marvel Universe. This prelude issue covered most of the Marvel Universes history as it is known on the planet Earth.

One page 10, the location that X-51 stumbles across is the Blue Area of the moon. Constructed long ago by the alien Kree. It is the home of Uatu the Watcher and was once home to the Inhumans. It's known for being the only area on the moon that has an atmosphere that can sustain life.

Page 11 panels 2 shows a blaster, and on panel 3 we see scorch marks on the ground. X-51 is in the location in which Dark Phoenix killed herself for the sake of the universe in X-Men #137.

Page 20: The Deviants on panel 3 were the Celestial's first attempt at mutating humanity. They first appeared in The Eternals #1 as well as their next creations shown in panel 4, the Eternals.

Page 21: This one page spread shows of the Deviants subterranean world of Lemuria located deep below the Earth's surface, as well as the Eternals home Olympia, which is located in Greece. The Eternal Ajax (First appearance Eternals #2) is seen flying towards Olympia.

Page 23: The hidden city of Attilan first appeared in Fantastic Four #45. It was originally located Two hundred miles southwest of Iceland. It was later relocated to the Himalayan Mountain range in China, until finally it was moved to the Blue Area of the Moon. Each time it was moved it was to avoid being found by the rest of humanity.

Page 26-27 Panel 2: In the second we see a Barbarian who could either be Conan (first appearance in Conan #1) or Kull (first appearing in Kull and the Barbarians #1) Both are characters that were part of Marvel continuity but were owned by other parties. Marvel no longer holds the rights to either character, and this probably explains why the barbarian in question has his back turned to the reader, let alone not being mentioned by name.

Page 30: Panel 1 shows the Invaders consisting of the Original Human Torch, Sub-Mariner, Bucky, Captain America and Toro. The team was the first group of heroes during World War 2. They first appeared as a team in Avengers #71. Toro was the sidekick to the original Human Torch he first appeared in Human Torch Comics #3. In panel 2 we see the Red Skull (John Schmidt) standing to the left of Adolf Hitler. The Red Skull is Captain America's arch nemesis, he first appeared in Captain America Comics #2.

Page 32-33: Features a number of the "Marvel Monsters" that were popular in the 1950's. After the war, popularity in super-hero comics flagged and comics turned to horror, science fiction, romance and drama. Marvel created a number of monsters for their horror and science fiction tales, some of these creatures are pictured here, from left to right they are: Groot (top left, first appeared in Tales to Astonish #13), The Brute That Walks (First appearance Journey Into Mystery #65), The Glob (first appearance Strange Tales #88) and others

Page 36: Panel one shows the second Human Torch (Johnny Storm) trying to revive the memories of the Sub-Mariner, this happened in Fantastic Four #4. Panel two shows Namor finding Atlantis deserted, this happened in Fantastic Four #6. His attack on New York City with the monster Giganto shown in panel 4 happened in Fantastic Four #4. Namor attacking the Eskimo's with the block of ice that contained the frozen body of Captain America happened in Avengers #4.

The first variant is part of a larger work of art by artist Alex Ross. Putting all the covers together in the proper order shows a larger picture. This particular cover shows the hand of the Golden Age Human Torch. This cover had a second printing. The 2nd printing of this cover featured a blue "X" in the Earth X title.

The second Variant is a Dynamic Forces special edition. This cover features a picture of the Earth surrounded by various Silver Age Marvel characters. The Human Torch, Daredevil (in red costume), Dr. Strange, Spider-Man, Thor, Hulk and Captain America are all represented on this cover as they appeared in the early 1960's.